Switch equipped male electric plug



April 1939- F. LOTTRIDGE 2,153,721

SWITCH EQUIPPED MALE ELECTRIC PLUG Filed May 26, 1938 Inventor A iiorneys Patented Apr. 11, 1939 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to an electric male plug containing switch means, the general object of the invention being to provide means whereby the prongs of the plug are normally disconnected from the circuit so as to be moved into circuit completing position when the prongs are inserted in the slots of a female member and the circuit will be broken when the prongs are removed from the female member, thus eliminating any danger of one being shocked by handling the male plug.

Another object of the invention is to so construct and arrange the parts, that the prongs are held against movement when they are not in the female member so that it will not be possible to complete the circuit to the prongs.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claims.

In describing the invention in detail, reference will be had to the accompanying drawing, wherein like characters denote like or corresponding parts throughout these several views, and in which:

Figure 1 is a longitudinal sectional view through a male plug constructed in accordance with this invention.

Fig. 2 is a view of the inner face of the prong carrying disk of the plug with the parts in inoperative position.

Fig. 3 is a similar view, but showing the parts in operative or circuit completing position.

Fig. 4 is a view of one of the prong members.

Inthis drawing, the numeral I indicates the body of the male plug and the numeral 2 indicates the disk which closes the lower end of the body and is suitably held in position. Of course the body and the disk are of non-conducting material and said disk has a pair of large holes therein through which the prongs 3 pass. Each prong is formed with a spiral part 4, a cylindrical part 5 which fits in the opening for rotary movement, and a disk-like head part 6 which rests on the inner face of the disk. This part 6 has a tongue I projecting from a peripheral portion thereof and an eccentric pin 8 projects from the upper face of the part 6. A flat bar 9 of nonconducting material has holes in its ends for simultaneously by the insertion of the parts 4 in the slots of a female member, said prong members will partly rotate in unison.

A pair of grooves I0 is formed in the upper face of the disk 2, one adjacent each prong member, and an arc-shaped spring contact member I I is placed in each groove and is held therein by a screw l2, passing through an end portion thereof into the disk. The inner end of each member I I is turned upwardly as shown at I3 to form a stop.

When the male plug is disconnected from a female member, the parts are in the position shown in Fig. 2, so that no current can pass from the conductors I4 which are electrically connected to the members II by the screws l2 and thus no current will pass through the prongs, so that these prongs can be handled without one being shocked. However, when the prongs are inserted into the slots of the female member the spiral parts 4 entering the slots will impart a partial rotary movement to the prong members, so that the tongues 'I will ride over the contact members II and thus the prong members will be electrically connected with the conductors I4 so that current will pass through the prong members to the female members and the conductors attached thereto. Thus with this invention, the male plug can be connected with the electric supply as there is no danger of one getting a shock by handling the prong members as they are disconnected from the supply, until they are inserted in the slots of a female member. The spiral parts 4 are so made as to govern the distance they will be allowed to turn, which distance will only be great enough to make and break contact and give proper clearance between the off and on positions, and never far enough to allow the plate 9 to arrive at the on center position. This type of plug will work equally as well in a three wire circuit, the only difference in the three wire circuitbeing that the two ungrounded wires will be attached to conductors and work as described above, but the third or grounded wire will be attached to a straight conductor not of the spiral type and this will be stationary.

It is thought from the foregoing description that the advantages and novel features of the invention will be readily apparent.

It is to be understood that changes may be receiving the pins 8 of the two prong members and the parts are so arranged that it will be impossible to move or partly rotate the two prong members by an attempt to turn one prong member, though the two prong members are turned made in the construction and in the combination and arrangement of the several parts provided that such changes fall within the scope of the appended claims.

What is claimed as new is:

1. In an electric device of the class described, a body, a pair of contacts in the body, conductors connected with the contacts, a pair of prong members rotatably supported by the body and having tongues connected to their ends which are located in the body, the projecting parts of said prong members being of spiral shape, whereby when said parts are inserted into the slots of a female member, the prong members will be partly rotated to place the tonguesin engagement with the contacts, the tongues moving out of engagement with the contacts when the prong mem-- bers are withdrawn from the slots of the female member.

2. In an electric device of the class described, a body, a pair of contacts in the body, conductors connected with the contacts, a pair of prong members rotatably supported by the body and having tongues connected to their ends which are located in the body, the projecting parts of said prong members being of spiral shape, where-' by when said parts are inserted into theslots of a female member, the prong members will be partly rotated to place the tongues in engagement with the contacts, the tongues moving out of engagement with the contacts when the prong members are withdrawn from the slots of the female member, an eccentric pin on the inner end of the prong member, a bar of non-conducting material having holes in its ends receiving the pins.

3. A male electric plug comprising a body,- a disk closing one end of the body and having a pair of holes therein, a pair of prong members each having a head at its inner end, a cylindrical portion under the head rotatably arranged in a hole, and the rest of the prong member being of spiral shape, each head having an eccentric pin thereon, a bar of non-conducting material having holes in its ends receiving the pins, a tongue on the peripheral portion of each head, contact members connected with the inner face of the disk and engaged by the tongues when the prong members are inserted into the slots of a female member, said prongs moving out of engagement with the contact members When the prong members are withdrawn from the female member and conductors entering the body and connected with the contact members.

FRED L. LOTTRIDGE. 

